The present invention relates to a polytrimethylene terephthalate yarn suitable for clothing use, a false-twist textured yarn using the same and a method for producing the same. More specifically the present invention relates to a polytrimethylene terephthalate multifilamentary yarn suitable for a stretch clothing such as sportswear, innerwear or outerwear, a false-twist textured yarn using the same and an industrial method for continuously producing the same for a long time while maintaining a high quality.
A polyethylene terephthalate (hereinafter referred to as PET) fiber has been mass-produced around the world as a synthetic fiber most suitable for a clothing use and this has developed to a major industry.
On the other hand, a polytrimethylene terephthalate (hereinafter referred to as PTT) fiber has been known from prior arts such as those disclosed in (A) Japanese Unexamined Patent Publication Nos. 52-5320, (B) 52-8123, (C) 52-8124, (D) 58-104216, (E) J. Polymer Science; Polymer Physics Edition Vol. 14, pages 263 to 274 (1976), and (F) Chemical Fibers International Vol. 45 (April), pages 110 to 111 (1995). These prior arts, however, merely describe a basic property of, the PTT fiber and a basic method for producing the PTT fiber. That is, these prior arts have not matured to a level suitable for industrially producing PTT fiber, and the resultant PTT fiber also has not reached a quality level capable of industrially producing a knit or woven fabric.
For example, while the prior art (F) discloses that PTT fiber is characterized by a smaller Young""s modulus (better in softness) and a higher stretch recovery (larger in elastic limit; more elastic) than PET fiber due to the solid structure of PTT polymer, designs of physical property and quality suitable for uses in which such characteristics are useful have not yet become apparent.
In the melt-spinning of polyester or nylon, if the spinning operation continues for a predetermined time, contaminant of decomposed polymer is adhered to the periphery of a spinning orifice. Such contamination is generally referred to as a white-eye phenomenon or an eye-mucus phenomenon. The contaminant is liable to disturb the smooth fiber formation and finally results in the breakage of multifilamentary yarn to disable the continuation of the spinning operation. To industrially avoid such a problem, it is usual to wipe off the contaminant from the surface of the spinneret at an constant period so that the smooth spinning state is maintained. Since the wiping operation must be carried out while interrupting the spinning, the wiping period is preferably longer, usually 24 hours or more on account of the working efficiency and the unit consumption of raw polymer.
Japanese Unexamined Patent Publication No. 11-200143 describes that PTT is more liable to deteriorate, due to heat or oxidation, than PET, whereby the deposition of the contaminant on the periphery of the spinning orifice becomes more significant during the spinning of PTT than PET and the wiping period must be shorter. To extend the wiping period, there are disclosed means for coating the surface of the spinneret with a lubricant of special composition and means for limiting a surface area A of polymer passing through a single orifice of the spinneret per unit time in a range from 5000 to 30000 mm2/min. In this regard, A is defined by the following equation:
A(mm2/min)=(Vxc3x97M)/(xcfx81xc3x97S)
wherein V is a discharge rate of polymer per single orifice (g/min), xcfx81 is a density of polymer (g/mm3), S is a cross-sectional area of an orifice (mm2) and M is a peripheral length of an orifice (mm).
However, in this prior art, none of constituents of PTT multifilamentary yarn are most suitable for stretch clothing. Also, there is no description of the effect of an intrinsic viscosity of PTT on the wiping period, and an available wiping period is at most approximately 36 hours. Further, there is no suggestion of a range of A suitable (industrially favorable) for the respective single-fiber size.
Since an elastomeric fiber such as polyurethane fiber has appeared, stretch clothing has rapidly been developed in the field of sportswear, innerwear, pantyhose and outerwear. For example, there are a mixed knit clothing of polyurethane fiber with nylon fiber or PET fiber (for an innerwear) and pantyhose formed of a covering yarn in which polyurethane fiber is covered with nylon fiber or a knit or woven fabric formed of composite fibers (a latent crimp yarn) composed of polyurethane fiber and PET fiber.
However, these prior art products are insufficient because there is a limitation in characteristic or cost thereof. In view of the above-mentioned circumstances, various types of stretch clothing are desired and new synthetic fibers suitable for the stretch clothing are expected.
An object of the present invention is to provide a PTT multifilamentary yarn, composed of high-quality PTT fibers rich in softness and excellent in elasticity, which is suitable for a stretch clothing excellent in stretch-back property, and a method capable for producing the same at a high yield.
A high stretch-back property means a nature of rubber in which a proper elongation is obtained when the fiber or the fabric is stretched, together with the increasing resistant feeling as it is stretched, which elongation is promptly returned back to the original state when the stretching force is released. In the stretch clothing, a crimped yarn of synthetic fiber such as a false-twist textured yarn is usually used.
Another object of the present invention is to provide a false-twist textured yarn suitable for the stretch clothing.
To achieve the above objects, the present invention is defined as follows:
A first aspect of the present invention is a PTT multifilamentary yarn formed of single filaments, having a circular cross-section, of PTT composed of 95 mol % or more of trimethylene tetephthalate repeating units and 5 mol %, or less of other ester repeating units, characterized in that the PTT multifilamentary yarn satisfies the following conditions (1) to (4):
(1) An intrinsic viscosity in a range from 0.7 to 1.1 dl/g
(2) A single-filament size in a range from 3.3 to 8.9 dtex
(3) An elongation at break in a range from 36to 60%, and
(4) A fluctuation value of yarn size (U %) of 1.2% or less
A second aspect of the present invention is a half-drawn PTT multifilamentary yarn formed of single filaments, having a circular cross-section, of PTT composed of 95 mol % or more of trimethylene terephthalate repeating units and 5 mol % or less of other ester repeating units, characterized in that the PTT multifilamentary yarn satisfies the following conditions (1) to (4,):
(1) An intrinsic viscosity in a range from 0.7 to 1.1 dl/g
(2) A single-filament-size in a range from 3.9 to 13.3 dtex
(3) An elongation at break in a range from 61 to 120%, and
(4) A fluctuation value of yarn size (U %) of 2% or less
A third aspect of the present invention is a false-twist textured PTT yarn obtained by false-twisting or draw false-twisting the PTT multifilamentary yarn defined by the first aspect or the half-drawn PTT yarn defined by the second aspect.
A fourth aspect of the present invention is a method for producing a PTT multifilamentary yarn or half-drawn multifilamentary yarn formed of single filaments, having a circular cross-section and an intrinsic viscosity [xcex7] in a range from 0.7 to 1.3 dl/g, of PTT composed of 95 mol % or more of trimethylene terephthalate repeating units and 5 mol % or less of other ester repeating units, characterized in that the PTT yarn is produced under the following conditions (1) to (4):
(1) The distances between centers of spinning orifices is 5 mm or more.
(2) The spinning temperature is in a range from 255 to 275xc2x0 C.
(3) The surface temperature of a spinneret is 255xc2x0 C. or higher.
(4) Vxc3x97[xcex7] is in a range from 5 to 12 (m/min)(dl/g)
wherein V represents a linear discharge speed (m/min) of melted PTT.